Solvent extraction process for recovery of uranium from phosphoric acid (25-55% P2O5)

ABSTRACT

An improved process of extraction of uranium from phosphoric acid and in particular uranium VI from phosphoric acid especially strong phosphoric acid using a selective synergistic extractant mix of an organo-phosphorous acid and a neutral extraction agent. The process basically involves the steps of extraction comprising contacting said acid with a selective synergistic extractant system of di-nonyl phenyl phosphoric acid (DNPPA) and a neutral agent selected from di-butyl butyl phosphonate (DBBP) and tri-n-octyl phosphine oxide (TOPO); and recovering the uranium values from the loaded organic phase. The above process would provide for an improved process for recovery of uranium both from weak and strong phosphoric acids using a stable and relatively cheap extractant system. The process is directed to improved recovery of U-VI from phosphoric acid by way of a simple, industrially applicable and cost-effective process.

[0001] The present invention relates to an improved process ofextraction of uranium from phosphoric acid and in particular uranium VIfrom phosphoric acid especially strong phosphoric acid using a selectivesynergistic extractant mix of an organo-phosphorous acid and a neutralextraction agent.

[0002] Phosphates are well known to be an important sustainablesecondary source of uranium. While methods of uranium extraction such asion-exchange, membrane separation and precipitation are well known, themethod of solvent extraction of uranium has been found to be asuccessful process for industrial recovery of uranium from phosphates.

[0003] It is well known to carry out uranium recovery from wet processphosphoric acid obtained via sulfuric acid route. There are variousknown solvent extraction processes, which include the OPPA process,which utilizes octyl pyrophosphoric acid as the extractant. This solventis inexpensive but is found to be highly unstable especially during theexposure to HF, which is needed for back extraction.

[0004] It is also known to carry out solvent extraction of uranium usingthe OPAP process which involves the use of octyl phenyl acid phosphateconsisting of mixture of mono octyl phenyl phosphoric acid (MOPPA) anddi-octyl phenyl phosphoric acid (DOPPA). It is characterized with highextraction of uranium. However, it has limited solubility in diluentslike kerosene and stability although comparatively better than OPPA isnot very high. Moreover, the selectivity is also not very high.

[0005] U.S. Pat. No. 4,302,427 discloses the uranium extraction usingthe solvent mixture of di-(2- ethyl hexyl) phosphoric acid (D2EHPA) andtri-n-octyl phosphine oxide (TOPO) in a phosphoric acid immiscibleorganic solvent. U.S. Pat. No. 4,778,663 discloses a further process ofrecovery of uranium from wet process phosphoric acid involving the useof a combination of dialkyl phosphoric acid and mixture of trialkylphosphine oxides. Such processes are characterized with low distributionratio of uranium and essentially requires the use of relativelyexpensive extractant component, which is TOPO.

[0006] U.S. Pat. No. 4,238,457 discloses the use of a first stageextraction using organic solvent consisting essentially ofdialkylphosphoric acid and trialkylphosphine oxide dissolved in an inertand unreactive organic solvent followed by a second stage re-extractionusing ammonium hydroxide and ammonium carbonate. Such a process iscost-extensive and yields a product of low purity.

[0007] Moreover, solvent extraction processes that have been reported assuccessful for extraction of hexavalent uranium—the form in whichuranium is generally present in phosphoric acid—involve extraction by amixture of an organo-phosphorous acid with a neutral synergist. Thus,di-(2-ethyl hexyl) phosphoric acid (D2EHPA)—tri-n-butyl phosphate (TBP),D2EHPA-di-butyl butyl phosphonate (DBBP) and D2EHPA-tri-n-octylphosphine oxide (TOPO) combinations have been reported. Results on DOPPAand di-nonyl phenyl phosphoric acid (DNPPA) have also been reported withtheir mono-ester components for extraction of tetravalent form ofuranium.

[0008] It would be evident from the above that for extraction of uraniumfrom phosphoric acids whether U-IV or U-VI is known to involve use ofthe combination of a organo-phosphorous acid as the basic component anda synergistic agent. Although this is generally known, it is extremelydifficult to ascertain the specific combinations of phosphoric acid andthe synergistic extractant agent and conditions for extraction whichcould achieve the desired extraction and which would be industriallyapplicable and be cost effective.

[0009] Importantly, lack of clear knowledge on the mechanism ofextraction even for known extraction systems makes it extremelydifficult to reach to a selective combination which would provide forbetter extraction and would also be cost effective. There are instanceswhere apart from selection of the acid/agent for extraction, theproportion in which the two compounds acid and the agent are useddetermine whether it would have a synergistic effect or an antagonisticeffect. This made it all the more difficult to identify the selectivecombination of extractant, which would provide the improved extractionby using a cost effective process. Added to the above, the knowledge ofextractant for extraction from weak phosphoric acid does not have directrelevance on the selection of the extractant for extraction from strongacids. This made it difficult to provide extraction systems for strongphosphoric acids.

OBJECT OF THE INVENTION

[0010] It is thus the basic object of the present invention to providefor an improved process for recovery of uranium both from weak andstrong phosphoric acids using a stable and relatively cheap extractantsystem.

[0011] Another object of the present invention is directed to providefor an improved process of recovery of U-VI from strong phosphoric acidusing a novel selective combination of an organo-phosphorous acid and aneutral synergistic agent.

[0012] Yet further object of the present invention is to provide for asynergistic combination of a organo-phosphorous acid and a neutralsynergistic agent which would provide for improved recovery of U-VI fromphosphoric acid by way of a simple, industrially applicable andcost-effective process.

[0013] Yet further object of the present invention is directed toprovide for a synergistic combination of the organo-phosphorous acid andTOPO/DBBP which would provide for selective and high purityyield/extraction of U-VI both from weak as well as strong phosphoricacids.

SUMMARY OF THE INVENTION

[0014] Thus according to the present invention there is provided animproved process for extraction of uranium from wet process phosphoricacid comprising:

[0015] a. steps of extraction comprising contacting said acid with aselective synergistic extractant system of di-nonyl phenyl phosphoricacid (DNPPA) and a neutral agent selected from di-butyl butylphosphonate (DBBP) and tri-n-octyl phosphine oxide (TOPO); and

[0016] b. recovering the uranium values from the loaded organic phase.

[0017] In accordance with one preferred aspect of the present inventionthe improved process for extraction of uranium from weak phosphoric acid(containing 26-30% P₂O₅) comprises:

[0018] a. steps of extraction comprising contacting said acid with saidselective synergistic extractant mix of di-nonyl phenyl phosphorous acid(DNPPA) and di-butyl butyl phosphonate (DBBP) after appropriatedilution; and

[0019] b. recovering the uranium values from the loaded organic phase.

[0020] In accordance with another preferred aspect of the presentinvention the improved process for extraction of uranium from strongphosphoric acid (containing 30-55% P₂O₅) comprises:

[0021] a. steps of extraction comprising contacting said acid afterappropriate dilution with a selective synergistic extractant mix ofdi-nonyl phenyl phosphoric acid (DNPPA) and tri-n-octyl phosphine oxide(TOPO); and

[0022] b. recovering the uranium values from the loaded organic phase.

[0023] Preferably, in the above discussed processes of the presentinvention the selective mole ratio of the extractant mix comprising ofsaid acid DNPPA and the agent DBBP/TOPO comprise mole ratio of 0.05 to0.20 M DBBP:0.2 M DNPPA and 0.05 to 0.155 M of TOPO:0.2 M DNPPA. It wasfound that the extraction increased with the increase in the level ofthe synergistic reagent used. However, it was identified that theoptimum mole ratio of synergistic reagent (DBBP/TOPO) with extractant is1:2.

[0024] Moreover, in the above disclosed processes of the invention, bothfor the weak phosphoric acid as well as the strong phosphoric acid,prior to said step of extraction the acid is subjected to pre-treatmentcomprising steps of separation of suspended solids, separation of humicmatter and oxidation. For the purpose, the humic matter wascharacterized by infrared (IR) spectra. It was found that long chainpolymeric flocculent used for separation of suspended solids fromfreshly produced acid was also effective in initial removal of organicmatter. Residual humic matter, not removed by clari-flocculation, wasremoved by carbon adsorption. As an alternative “solvent scrubbing”method can also be used. After humic matter separation, oxidation withair sparging was followed by polishing oxidation with hydrogen peroxidecarried out in stages. Clear oxidized acid was subjected to solventextraction.

[0025] Preferably, in the above process of the invention, after theextraction is effected, the barren acid is subjected to post-treatmentfor entrained solvent recovery. Different methods of stripping such asammonium carbonate, HF or strong H₃PO₄ under reducing conditions can befollowed.

[0026] In accordance with another aspect of the invention it was foundthat the phase continuity in the mixer played an important role,especially for MGA. With aqueous continuous operation, entrainmentexceeded 300 mL/m³, whereas with organic continuous, it was 130-260mL/m³. Use of a coalescer with a residence time of 13 min reducedentrainment to 18-26 mL/m³.

[0027] The details of the invention, its objects and advantages areexplained herein in greater detail in relation to the non-limitingexemplary illustrations.

EXAMPLES

[0028] Preparation of Extractant Mix

[0029] DNPPA was synthesized by the known procedure. A mixture of di-and mono-esters of nonyl phenyl phosphoric acid was obtained by reactingp-nonyl phenol with phosphorous oxy-chloride in the presence of pyridinein mole ratio of 2:1:2. The reaction mixture was hydrolyzed with excessof 6 M HCl at 80° C. for 12 h. The di- and mono-esters were separated byextraction from benzene solution with 70% methanol. The unreacted nonylphenol and neutral compounds were. separated by loading the benzenelayer with neodymium (Nd) and precipitating the Nd-diester salt inexcess acetone. Di-ester was obtained by dissolving the salt in benzeneand stripping the Nd with oxalic acid. The concentrations of mono- anddi-esters were determined by potentiometric titration with alkali inethanol medium. The separated di-ester fraction contained˜2% neutral andbalance di-ester. Commercially available DBBP and TOPO of 95% puritywere used for the work. The diluent used was the aliphatic fraction ofrefined kerosene. Gas chromatography confirmed composition (%) as C₁₀(14.7), C₁₁ (26.9), C₁₂ (26.2), C₁₃ (15.8), C₁₄ (16.1), with aromaticcontent˜0.1%. Flash point was 73° C. and density 751 kg/m³. Importantly,the low aromatic content was preferred as it was found to be importantfor reducing entrainment losses, especially while processing MGA.

[0030] Specifications of Phosphoric Acid Used

[0031] Phosphate rock samples from operating plants as well as reservesknown to contain uranium were used to make phosphoric acid. Leaching ofrock was carried out with sulfuric acid at 65° C. for 2 h in thepresence of H₂O₂ as the oxidising agent. The WPA in a typical experimentanalyzed (g/L) U₃O₈ (0.11), SO₃ (45), Fe₂O₃ (3.9), Al₂O₃ (3.9), CaO(13.3), MgO (2.6), F (23). This acid was concentrated by evaporation ina water bath to >8 M H₃PO₄ for use in later stages of the work. Bothweak and strong acids were subjected to pre-treatment which includedseparation of suspended solids, separation of humic matter andoxidation. After pre-treatment, extraction was carried out and barrenacid subjected to post-treatment for entrained solvent recovery.

[0032] Apparatus Used

[0033] Tests at 1000 L/h using a 3.5-m diameter clari-flocculator, 0.5-mdiameter carbon column and polypropylene mixer-settlers. Entrainedsolvent recovery was carried out using a laminar coalescer and flotationcell.

Example I

[0034] A comparative study of the effect of the selective synergisticreagent with DNPPA was studied as hereunder:

[0035] For the purpose, studies were carried out on equilibriumdistribution ratio (D) for extraction from synthetic 5.8 M phosphoricacid containing 0.43 g/l U308 using only DNPPA 0.2 M, only DBBP (0.1 M),only TOPO (0.1 M) and the selective combination of DNPPA (0.2M)+DBBPITOPO (0.1 M) and the results obtained are detailed hereunder inTABLE 1: TABLE 1 Extractant DNPPA DBBP TOPO DNPPA + DBBP DNPPA + TOPO(0.2 M) (0.1 M) (0.1 M) (0.2M) + (0.1M) (0.2M) + (0.1M) D 0.102 0.020.03 2.00 2.97 Values

[0036] It would be evident from the above that the extractant mix ofDNPPA+DBBP/TOPO achieved a synergistic improved extraction than thatachieved in the extraction of only DNPPA and only DBBP/TOPO.

Example II

[0037] The extraction achieved by the synergistic extractant mix ofDNPPA+DBBP/TOPO vis-a-vis the conventional D2EHPA+TOPO was next studiedas discussed hereunder.

[0038] The data on equilibrium distribution ratio (D) for extractionfrom synthetic 5.8 M phosphoric acid containing 0.43 g/L U₃O₈ usingDNPPA vis-á-vis D2EHPA in combination with DBBP/TOPO are provided inTable 2 hereunder: TABLE 2 Effect of synergistic reagent on extractionof uranium (VI) - D values Serial DBBP TOPO Mole D number (M) (M) ratioD2EHPA DNPPA 1 0.05  — 4:1 0.38 1.74 2 0.066 — 3:1 0.40 1.85 3 0.10  —2:1 0.46 2.00 4 0.155 — 1.33:1 0.41 1.52 5 0.20  — 1:1 0.32 1.45 6 —0.05 4:1 0.90 2.50 7 — 0.10 2:1 0.79 2.97 8 —  0.155 1.33:1 0.68 2.84

[0039] The above results confirmed that D increases with increase inconcentration of synergistic reagent to a certain level after which Ddecreases. The optimum mole ratio of synergistic reagent (DBBP/TOPO)with extractant was 1:2, vis-á-vis the case of D2EHPA/TOPO where it was1:4. TOPO showed higher D value than DBBP. In view of the higher cost ofTOPO in comparison with DBBP, the preferred reagent for extraction ofuranium from WPA was found to be DBBP.

Example III

[0040] Effect of DNPPA concentration in the extraction process was nextstudied keeping the mole ratio of synergistic reagent constant. Theresults are given in Table 3. TABLE 3 Effect of DNPPA concentration onextraction of U (VI) - D values D in 5.8 M D in 8 M DNPPA H₃ PO₄ H₃ PO₄Serial concentration With With With number (M) DBBP TOPO TOPO 1 0.1 —2.14  0.49 2 0.2 1.95 — — 3 0.3 2.25 — — 4 0.4 — 7.05  1.08 5 0.5 3.38 —2.4 6 0.6 — 9.1  2.6

[0041] The extraction of uranium from 5.8 and 8 M H₃PO₄ increased withincrease in concentration of DNPPA, the increase approximates a powerlaw with an exponent of 0.6. With 0.6 M DNPPA+0.3 M TOPO as theextractant and 8 M H₃PO₄ as aqueous feed, the D value of 2.6 wasachieved. The extraction of U (VI) from 8 M H₃PO₄ was also carried outusing 0.5 M D2EHPA+0.125 M TOPO and 1.0 M D2EHPA+0.25 M TOPO as theextractants. The D values were found to be 0.63 and 1.57, respectively,which were significantly lower than the values obtained in the DNPPAsystem.

Example IV

[0042] The relative strength of the extractant mix of the invention inextraction of U (VI) values vis-á-vis other known extractants for U (VI)was studied and the result are detailed hereunder in Table 4. TABLE 4 DD SI. No. Extractants U-form Molar 8 M H₃PO₄ 5.8 M H₃PO₄ 1. DNPPA +MNPPA U(IV) 0.1 M + 0.1 M 2.81 9.4 2. D2EHPA + TOPO U(VI) 0.2 M + 0.05 M— 0.9 3. DNPPA + TOPO U(VI) 0.2 M + 0.05 M 0.49 2.50 4. D2EHPA + DBBPU(VI) 0.2 M + 0.1 M — 0.46 5. DNPPA + DBBP U(VI) 0.2 M + 0.1 M — 2.00 6.D2EHPA + DBBP U(VI) 0.5 M + 0.25 M 0.32 0.46 7. DNPPA + DBBP U(VI) 0.5 +0.25 M 2.4  3.38 8. DNPPA + TOPO U(VI) 0.6 M + 3 M 2.6  9.1

[0043] It would be well apparent from the above that the synergisticextractant mix of the persent invention is found to provide for betterand improved extractants of Uranium (VI) from weak (5.8 M) and strong (8M) phosphoric acid vis-à-vis the other presently known extractants.

Example V

[0044] Based on the above favorable results further studies oncounter-current extraction from WPA was carried out as detailedhereunder:

[0045] For the purpose, the A/O ratio of 2.5, contact time of 1.5 minand five stages were used. Tests were carried out with WPA (5.8 MH₃PO₄), analyzing 0.11 g U₃O₈/L as aqueous feed. The organic phaseconsisting of 0.5 M DNPPA+0.25 M DBBP was used as an extractant. Afterreaching steady state, the stage-wise uranium analyses in both organicand aqueous phases were carried out. The extraction profile is given inTable 5. From the results, it was found that >93% of the uranium wasextracted. TABLE 5 Counter current extraction of uranium (VI) fromWPA/MGA with different extractants. Uranium concentration Uraniumconcentration Uranium concentration (g/L) (g/L) (g/L) StageDNPPA-DBBP-WPA DNPPA-DBBP-MGA D2EHPA-TOPO-MGA No. Org. phase Aq. phaseOrg. phase Aq. phase Org. phase Aq. phase 1 0.08 <0.01 0.032 0.030 0.030.037 2 0.12 0.055 0.042 0.049 0.05 0.053 3 0.15 0.065 0.049 0.063 0.0550.060 4 0.18 0.075 0.065 0.083 0.065 0.078 5 0.21 0.100 0.087 0.1100.082 0.114

[0046] Two systems, one consisting of 1 M D2EHPA+0.25 M TOPO and theother of 0.5 M DNPPA+0.25 M DBBP, were tested separately in five stagesof counter-current extraction and A/O ratio of 1.5. The feed contained0.155 g U₃O₈/L. Contact time was 3 min. At steady state, organic andaqueous phases were analyzed and results are given in Table 5. Uraniumrecovery is found to be 80% in both systems. Importantly furtheradditional three stages were found to increase the recovery to >90%.

[0047] Stripping of Uranium from Extract

[0048] The medium for stripping of uranium was 8-12 M H₃PO₄, containing10 g Fe⁺²/L at 55-60° C. Using this reagent, the effect of phase ratiowas studied. At phase ratios (O/A) of 10 and 20, the D values were foundto be 0.03 and 0.015, respectively. In order to obtain concentrateduranium strip liquor, phase ratio of 20 was selected for five stages ofcounter-current stripping. Loaded organic phase containing 0.11 g U₃O₈/Lwas stripped into a product solution containing >2 g U₃O₈/L.

[0049] Purification of Uranium in a Second Cycle

[0050] The strip liquor collected in the first cycle using DNPPA-DBBPwas used as feed after dilution and oxidation of uranium for a secondcycle. The extractant used in the second cycle was 0.3 M D2EHPA+0.075 MTOPO. However, the phase ratio was increased in view of the dilute feedand the extract was scrubbed with dilute sulfuric acid. From the loadedorganic phase, uranium was stripped with 1-M ammonium carbonatesolution. The strip liquor filtered to remove traces of ironprecipitate. The uranium tri-carbonate solution contained excessammonium carbonate and pH was found to be 8.3. Uranium precipitation wascarried out using H₂O₂. The neutralization was carried out with sulfuricacid. In a pH range of 3-4, the uranium precipitation was complete(>99%). Uranium peroxide (UO₄. 2H₂O) was filtered, washed, dried andcalcined at 375° C. to obtain UO₃ powder of >99% purity.

Example VI

[0051] A further experimental extraction of U (VI) was carried outfollowing counter current extraction using the extractants mix of theinvention as discussed hereunder:

[0052] 100 litres of phosphoric acid of 45% P₂O₅ strength and containing15.5 gm uranium was contacted with 150 litres of solventcounter-currently in eight stages. The barren raffinate contained 0.9 gmuranium in 100 litres. The 150 litres of uranium loaded solvent,containing 14.6 gm uranium was stripped with 7.5 litres of the strippingacid (10 M H₃PO₄) to which scrap iron added was 75 gm. Eight contactstages were used. A product solution of 7.5 litres containing 14.5 gm ofU₃0₈ (>93% recovery) was obtained.

Example VlI

[0053] Tests to Ascertain the Stability of the Extractant

[0054] In two parallel experiments, aliquots of 0.5 M DNPPA+0.25 M DBBPwere mixed with 8 M phosphoric acid at room temperature and at 60° C.,respectively for 15 days. Samples of the organic phase were withdrawn atintervals and a standard uranium extraction test was carried out. Nodetectable change in D was found during this period indicating goodstability of the solvent towards strong acid and temperature.

[0055] The above process of the invention is thus suitable forindustrial operation.

[0056] The present invention thus provides for improvement in extractionof uranium from phosphoric acid by way of a selective extractantcomprising DNPPA in combination with synergistic reagents DBBP and TOPO,both for extraction on uranium (VI) from phosphoric acid (WPA/MGA).Distribution values obtained with DNPPA are higher than in the presentlyused systems, for commercial recovery of uranium from phosphoric acid.Preferably, for uranium recovery from WPA, DNPPA in combination withDBBP is most appropriate, while for uranium separation from MGA, DNPPAin combination with TOPO is found to be most suitable.

We claim:
 1. An improved process for extraction of uranium from wetprocess phosphoric acid comprising: a. steps of extraction comprisingcontacting said acid with a selective synergistic extractant system ofdi-nonyl phenyl phosphoric acid (DNPPA) and a neutral agent selectedfrom di-butyl butyl phosphonate (DBBP) and tri-n-octyl phosphine oxide(TOPO); and b. recovering the uranium values from the loaded organicphase.
 2. An improved process for extraction of uranium from wet processphosphoric acid as claimed in claim 1 wherein the extraction of uraniumfrom weak (26%-30% P₂O₅) phosphoric acid comprises: a. steps ofextraction comprising contacting said acid after appropriate dilutionwith said selective synergistic extractant mix of di-nonyl phenylphosphoric acid (DNPPA) and di-butyl butyl phosphonate (DBBP); and b.recovering the uranium values from the loaded organic phase.
 3. Animproved process for extraction of uranium from wet process phosphoricacid as claimed in claim 1 wherein the extraction of uranium from strongphosphorous acid (30-55% P₂O₅) comprises: a. steps of extractioncomprising contacting said acid after appropriate dilution with aselective synergistic extractant mix of di-nonyl phenyl phosphoric acid(DNPPA) and tri-n-octyl phosphine oxide (TOPO); and b. recovering theuranium values from the loaded organic phase.
 4. A process as claimed inclaim 1 wherein the selective mole ratio of the extractant mix usedcomprise of said acid DNPPA and the agent DBBP/TOPO in mole ratio of0.05 to 0.25M DBBP:0.2 to 0.5 M DNPPA and 0.05 to 0.33 M TOPO:0.1 to0.66 M DNPPA.
 5. A process as claimed in claim 4 wherein the selectivemole ratio of the extractant mix used comprise of said agent DBBP andthe DNPPA in amounts of 0.05 to 0.20 M DBBP:0.2 M DNPPA respectively. 6.A process as claimed in claim 4 wherein the selective mole ratio of theextractant mix used comprise of said agent TOPO and the acid DNPPA inamounts of 0.05 to 0.155 M TOPO:0.2 M DNPPA.
 7. A process as claimed inclaim 1 wherein the mole ratio of the synergistic reagent (DBBP/TOPO)with respect to DNPPA is 1:2.
 8. A process as claimed in claim 1 whereinprior to said step of extraction the acid is subjected to pre-treatmentcomprising steps of separation of suspended solids, separation of humicmatter and oxidation.
 9. A process as claimed in claim 8 wherein saidstep of pre-treatment comprise use of long chain polymeric flocculentfor initial separation of suspended solids from acid followed by carbonadsorption.
 10. A process as claimed in claim 8 wherein saidpre-treatment comprise solvent scrubbing.
 11. A process as claimed inclaim 8 wherein after humic matter separation, oxidation with airsparging was followed by polishing oxidation with hydrogen peroxide instages.
 12. A process as claimed in claim 1 wherein the barren acidafter extraction is subjected to post-treatment for entrained solventrecovery.
 13. A process as claimed in claim 1 wherein the selectiveextractant mix comprise DNPPA:DBBP/TOPO in the ratio of 0.2 M:0.1 Mrespectively.
 14. A process as claimed in claim 1 comprising countercurrent extraction of uranium from weak phosphoric acid using aqueous toorganic phase ratio of 4 to 1:1 to 1.5, preferably 2.5, contact time of0.5 to 4 minutes, preferably 1.5 to 2 minutes and involving 3 to 10stages of extraction preferably five to eight stages of extraction. 15.A process as claimed in claim 14 wherein the organic phase usedcomprises 0.5 M DNPPA and 0.25 M DBBP.
 16. A process as claimed in claim1 comprising counter current extraction of uranium from strongphosphoric acid using aqueous to organic phase ratio of 2 to 1:1 to 2,preferably 1.5, contact time of 1 to 5 minutes, preferably 2 to 4minutes and involving 4 to 12 stages of extraction preferably five toeight stages.
 17. A process as claimed in claim 16 wherein theextractant system used comprise 0.5 M DNPPA and 0.25 M DBBP.
 18. Aprocess as claimed in claim 1 comprising the method of recovery ofuranium from organic phase by stripping using one or more of ammoniumcarbonate, HF or the strong H₃PO₄ under reducing conditions.
 19. Aprocess as claimed in claim 18 wherein said medium for stripping ofuranium used is 8-12 M H₃PO₄ containing 10 g Fe⁺²/L at 55-60° C.
 20. Aprocess as claimed in claim 1 wherein said step of recovery of uraniumcomprises subjecting the strip liquor collected after first cyclerecovery using DNPPA-DBBP as feed after dilution and carrying outoxidation of uranium in a second cycle wherein the extractant used inthe second cycle is 0.3 M D2EHPA+0.075 M TOPO.
 21. A process as claimedin claim 20 wherein the extract was scrubbed with diluted sulfuric acid.22. A process as claimed in claim 21 wherein strip liquor was filteredto remove traces of iron precipitate.
 23. A process as claimed in claim22 wherein uranium precipitation was carried out using H₂O₂ followed byneutralization using sulfuric acid with pH maintained in the range of3-4 to thereby precipitate the uranium.